Heat shield assembly for aircraft wheel and brake assembly

ABSTRACT

A heat shield assembly for a wheel and brake assembly includes one or more torque bars that include a coupling device which cooperates with a portion of a heat shield (and more particularly heat shield sections) at a location axially outwardly remote from the inboard end of the heat shield so as to restrain radial outward movement of the heat shield. In another embodiment, the heat shield assembly includes heat shield carriers between which respective heat shield sections are axially inserted, and retainers are removably secured with respect to the carriers for blocking axial withdrawal of the heat shield sections from respective carriers. In another embodiment, heat shield carriers include a reversely bent edge portion defining a capture slot, and at least one aperture in the bent edge portion. A heat shield section has at one side thereof a first tab portion circumferentially inserted in the capture slot and at an opposite side thereof a second tab portion engaged in the aperture.

This application is a divisional of U.S. patent application Ser. No.11/324,977 filed Jan. 3, 2006, which is a divisional of U.S. patentapplication Ser. No. 10/268,606 filed on Oct. 10, 2002, which claims thebenefit of U.S. Provisional Application No. 60/328,875 filed Oct. 10,2001, all of which are hereby incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

The invention herein described relates to aircraft wheel and brakeassemblies and, more particularly, to improvements in heat shields andheat shield support structures.

BACKGROUND OF THE INVENTION

An aircraft wheel and brake assembly typically includes a heat shielddisposed between the wheel and brake disks to prevent conduction andradiation to the aircraft wheel of heat energy generated in the brakedisks during braking. Excessive temperatures in the aircraft wheel candamage the wheel and the aircraft tire. The heat shield also preventshot brake material ejected from the brake disks during braking frombeing slung against the inside of the wheel, which can also damage thewheel and further contribute to excessive temperatures.

An early example of a heat shield is described by U.S. Pat. No.3,051,528 issued in 1962 to R. R. Rogers. The Rogers heat shieldcomprises a multitude of curved heat shield sections disposed betweenadjacent drive keys. More recent examples are described by U.S. Pat. No.4,017,123 issued in 1977 to Horner et al. and U.S. Pat. No. 4,084,857issued in 1978 to VanderVeen. These heat shields also comprise curvedheat shield sections disposed between adjacent drive keys. The Horner etal. heat shield sections are captive between the drive key caps andledges formed on the drive keys. The ledges and drive keys areintegrally formed with the wheel, which is typical of wheel and brakeassemblies having steel disks. Horner et al. states that the heat shieldsections could be used with the removable keys presented in Rogers.However, exactly how this would be accomplished is not clear because theRogers drive keys do not have ledges or drive key caps. The VanderVeenheat shield section is captive between the drive key cap and anadditional cap having a pair of wings that extend from either side ofthe drive key. The drive keys are integrally formed with the wheel, andwings eliminate the need for the ledges of Horner et al. The heatshields described thus far are representative of the technologydeveloped for wheel and brake assemblies having steel brake disks withmetallic friction linings.

The advent of carbon/carbon brake disks instigated further developmentof heat shields. Carbon/carbon brakes generally operate at a much highertemperature than their steel counter-parts, which necessitated furthersteps to minimize conduction and radiation of heat energy into theaircraft wheel. Most wheel and brake assemblies having carbon/carbonbrakes now have removable torque bars that are spaced from the inside ofthe aircraft wheel, with attachments at both ends. This arrangementminimizes the conductive path from the torque bars to the wheel. Heatshield contact with the torque bars is preferably minimized for the samereasons. In addition, radiation is a major source of heat transfer fromcarbon/carbon brakes, which necessitates that the heat shield fullyencircle the brake disks with minimum holes or breaks that permit directradiation of heat energy to the aircraft wheel. Conduction is anothermajor source of heat transfer in carbon/carbon brakes, which isminimized by minimizing contact of the torque bars and heat shield withthe aircraft wheel. These considerations caused a significant departurefrom the earlier heat shield technology developed for steel brakes.

According to one prior art approach, a single piece full circle heatshield is attached to the wheel and brake assembly between the wheel andthe torque bars. The heat shield is spaced from both the torque bars andthe aircraft wheel in order to minimize heat conduction to the heatshield from the torque bars. The heat shield comprises two cylindricalstainless steel sheets spaced from each other, with insulation inbetween. A heat shield constructed in such manner, though certainly safeand effective, embodies some undesirable characteristics. For example,the shield tends to warp and buckle during use due to thermal expansionand contraction induced by braking cycles. In addition, removing adamaged heat shield generally requires removing all the torque bars fromthe aircraft wheel assembly.

Another heat shield is described in U.S. Pat. No. 5,002,342 issued in1991 to Dyko. The Dyko shield comprises a plurality of heat shieldsectors that together define a full circle heat shield. The edges of theheat shield are interleaved in a manner that permits relative expansionand contraction of the heat shield sectors induced by thermal gradients.Also, removal of a single heat shield requires only the removal of thosetorque bars corresponding to that sector. Thus, individual sectors maybe removed and replaced as necessary without replacing the entire heatshield. A similar heat shield having sectors connected by hinged edgesis described in U.S. Pat. No. 5,236,249 issued in 1993 to Han et al.

Further heat shield improvements are described in U.S. Pat. No.5,851,056 issued in 1998 to Hyde. The Hyde heat shield comprisesindividual heat shield sections disposed between adjacent torque barsand elongate heat shield carriers superposing the torque bars andengaging the heat shield sections. With such an arrangement, the heatshield sections are removable without loosening or removing any torquebars.

Although the Hyde heat shield is an effective heat shield, it andsimilarly designed heat shields exhibit undesirable characteristics.Since the wheel acts as part of the pressure vessel to contain tirepressure, there is limited structure to which the heat shield sectionsand carriers can be mounted. For example, the heat shield sections andcarriers of the Hyde heat shield are mounted at their axially inboardends to the wheel flange and extend axially into the tube well. Toprovide support deep within the tube well, the heat shield carriersinclude resilient bumpers at their axially outboard ends. The resilientbumpers contact the tube well and restrain radial movement of the heatshield carriers and also the heat shield sections engaged by thecarriers. During wheel spin up, the heat shield sections and carriersare forced radially outwardly and the resilient bumpers protect the tubewell from being scored. However, over time the resilient bumpers have atendency to degrade, which may cause the heat shield sections and/orcarriers to contact and/or abrade the protective coatings of the tubewell. Once the protective coating is removed, the wheel is susceptibleto corrosion which can lead to the wheel being prematurely removed fromservice.

In addition to solving the problem of wheel scoring by other than theuse of a bumper that is subject to degradation, there is a general needfor further improvements in heat shield systems that provide for easierassembly and withdrawal of individual heat shield sections and/orimproved performance of the heat shield.

SUMMARY OF THE INVENTION

The present invention provides several advances in the art of heatshield design and installation.

According to one aspect of the invention, a wheel and brake assemblycomprises a wheel including a tube well having an inboard end andoutboard end. At least one torque bar is attached to the tube well fortransferring torque from the wheel to brake components located radiallyinwardly of the tube well. The torque bar extends generally parallel tothe axis of rotation of the wheel and is spaced radially inwardly fromthe tube well. A heat shield is concentric with and disposed radiallyinwardly of the tube well, and has an inboard end attached to the tubewell. The torque bar includes a coupling device cooperating with aportion of the heat shield at a location axially outwardly remote fromthe inboard end of the heat shield so as to restrain radial outwardmovement of the heat shield.

In a preferred embodiment of the invention, the heat shield includes aplurality of circumferentially arranged heat shield sections and aplurality of carriers for removably attaching the heat shield sectionsto the wheel at respective torque bars. Each carrier has an inboard endattached to the tube well, and the coupling device of the respectivetorque bar cooperates with a portion of the carrier at a locationaxially outwardly remote from the inboard end of the carrier so as torestrain radial outward movement of the carrier. The coupling device islocated axially between, and preferably midway between, the inboard andoutboard ends of the torque bar. The coupling device includes, forexample, a button on the torque bar which interconnects with a keyholein heat shield carriers, or vice versa. The heat shield may also includea radially inwardly projecting offset portion to provide radial spacing,and therefore an air gap, between the heat shield and the torque bar. Apreferred coupling device has an enlarged head and a reduced width stemconnecting the head to the torque bar, and a preferred keyhole has anenlarged portion dimensioned to receive the head and a reduced widthportion for receiving the stem. As is also preferred, the couplingdevice is advantageously located midway along the circumferential spanof the torque bar.

The invention also provides a heat shield carrier for a wheel and brakeassembly, which carrier includes an elongated thin strip with anaperture at one end through which a bolt can pass for securing an end ofthe carrier to a wheel, and a keyhole intermediate the ends of the stripfor interconnecting with a button on a torque bar.

Also provided is a novel torque bar for a wheel and brake assembly. Thetorque bar includes an elongated bar having at one end an aperturethrough which a bolt can pass for securing an end of the bar to a wheeland configured at its opposite end for attachment to the wheel. A buttonis located intermediate the length of the bar for coupling with akeyhole in a carrier for a heat shield section.

According to another aspect of the invention, a heat shield assembly fora wheel and brake assembly, comprises a circumferential arrangement ofheat shield sections, a plurality of axially extending heat shieldcarriers between which respective heat shield sections are axiallyinserted, and at least one retainer removably secured with respect to arespective carrier for blocking axial withdrawal of the heat shieldsection from respective carriers.

In a preferred embodiment, the retainer is secured to an axial end ofthe carrier by an axially extending fastener. To this end, the carriermay include a radially extending flange at the axial end thereof. Theretainer and flange of the carrier include coacting anti-rotationelements.

Also, at least one of the carriers preferably has an axial stop againstwhich a portion of the respective heat shield section abuts to limit theextent of axial insertion of the heat shield section with respect to thecarrier. Each carrier may have on opposite sides thereof upper and lowertabs defining axially extending channels for receiving edge portions ofcircumferentially adjacent heat shield sections. The axial stop maycomprise any suitable projection obstructing axial movement of the heatshield section. An exemplary axial stop is formed by an axial end of oneof the tabs of the carrier. In this regard, each heat shield sectionincludes at a side edge thereof a projecting abutment for engaging theaxial stop.

According to a further aspect of the invention, a heat shield assemblyfor a wheel and brake assembly, includes a circumferential arrangementof axially extending heat shield carriers, each carrier having an edgeportion defining a capture slot opening circumferentially toward theopposite edge of the carrier, and at least one aperture in the edgeportion. A plurality of heat shield sections circumferentially extendbetween relatively adjacent carriers, and each heat shield sectionincludes at one side thereof a first tab portion circumferentiallyinserted in the capture slot and at an opposite side thereof a secondtab portion engaged in the aperture. As is preferred, the capture slotis formed by reversely bending the edge portion of the carrier back overitself.

In a preferred embodiment, each heat shield section has a relativelythick central insulating portion between the first and second tabportions. The first tab portion includes a first plurality of axiallyspaced apart tabs which define therebetween respective relief portions,and axially spaced apart apertures are correspondingly sized and axiallyspaced apart relative to the relief portions such that the firstplurality of axially spaced apart tabs align with the respectiveapertures. The second tab portion includes a second plurality of axiallyspaced apart tabs which are axially offset in relation to the firstplurality of axially spaced apart tabs, and the apertures arecorrespondingly sized and axially spaced apart relative to the secondplurality of axially spaced apart tabs such that the second plurality ofaxially spaced apart tabs may be aligned with the apertures for radialinsertion into the apertures.

According to another aspect of the invention, a wheel and brake assemblycomprises a wheel including a tube well having inboard end and outboardends. A plurality of circumferentially spaced apart torque bars areattached to the tube well for transferring torque from the wheel tobrake components located radially inwardly of the tube well. The torquebars extend generally parallel to the axis of rotation of the wheel andare spaced radially inwardly from the tube well. A plurality of heatshield sections extend circumferentially between relatively adjacentpairs of the torque bars. A plurality of axially extending heat shieldcarriers are attached to the torque bars and therebetween the heatshield sections are retained. The heat shield sections each include arelatively thick insulating portion and relatively thin edge portions atopposite sides of the relatively thick insulating portion. Therelatively thick insulating portion spans the space between relativelyadjacent torque bars. At least one of the edge portions is connected toa respective carrier and at least one of the edge portions extendsbetween the torque bar and the tube well.

The invention also provides a novel heat shield section for a wheel andbrake assembly. The heat shield section includes a relatively thickinsulating portion and relatively thin edge portions. One edge portiondefines a first tab for insertion into an axial slot in a carrier, andthe opposite edge portion includes a second tab for engagement in anaperture in a carrier. The first and second tabs are axially offset inrelation to one another.

The foregoing and other features of the invention are hereinafter fullydescribed and particularly pointed out in the claims, the followingdescription and the annexed drawings setting forth in detailillustrative embodiments of the invention, such being indicative,however, of but a few of the various ways in which the principles of theinvention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a wheel and brake assembly employinga heat shield assembly according to one embodiment of the invention.

FIG. 2 is an enlarged cross-sectional view of a heat shield assemblyshown in relation to the wheel and brake assembly of FIG. 1.

FIG. 3 is an arcuate portion of a front/inboard end view of the wheeland brake assembly of FIG. 1, looking into the wheel from the left sideof FIG. 1.

FIG. 4A is a perspective view of a torque bar used in the wheel andbrake assembly of FIG. 1.

FIG. 4B is a top view of the torque bar.

FIG. 4C is a longitudinal cross-sectional view of the torque bar takenalong the line 4C-4C of FIG. 4B.

FIG. 4D is a bottom view of the torque bar looking from the line 4D-4Dof FIG. 4C.

FIG. 4E is an enlarged transverse cross-sectional view of the torque bartaken along the line 4E-4E of FIG. 4B.

FIG. 4F is an end view of the torque bar as viewed from the line 4F-4Fof FIG. 4B.

FIG. 5A is a top view of a heat shield carrier used in the wheel andbrake assembly of FIG. 1.

FIG. 5B is a side elevational view of the heat shield carrier of FIG. 5Alooking from the line 5B-5B of FIG. 5A.

FIG. 5C is a bottom view of the heat shield carrier looking from theline 5C-5C of FIG. 5B.

FIG. 5D is an end view of the heat shield carrier as viewed from theline 5D-5D of FIG. 5C.

FIG. 5E is a partial transverse cross-sectional view of the heat shieldcarrier taken along the line 5E-5E of FIG. 5C.

FIG. 6A is a top view of a heat shield used in the wheel and brakeassembly of FIG. 1.

FIG. 6B is an end view of the heat shield looking from the line 6B-6B ofFIG. 6A.

FIG. 6C is a longitudinal cross-sectional view of the heat shield takenalong the line 6C-6C of FIG. 6A.

FIG. 7 is a top view of the heat shield section engaged with the heatshield carrier.

FIG. 8 is a cross-sectional view of a portion of a wheel and brakeassembly according to another embodiment of the invention, showing inparticular a heat shield assembly.

FIG. 9 is an arcuate portion of a front/inboard end view of the wheeland brake assembly, looking from the line 9-9 of FIG. 8.

FIG. 10 is an enlarged portion of FIG. 9.

FIG. 11 is a plan view looking from line 11-11 of FIG. 8.

FIG. 12 illustrates an alternative arrangement for axially coupling theheat shield section to the heat shield carrier.

FIG. 13 is a top view of a heat shield assembly according to a furtherembodiment of the invention, the heat shield assembly being shown in anunassembled condition.

FIG. 14 is an end view of the heat shield assembly of FIG. 13, lookingfrom the line 14-14 of FIG. 13, the heat shield assembly being shownrelative to a tube well and torque bar.

FIG. 15 is a cross-sectional view of a portion of the heat shieldassembly of FIG. 13, with one of two relatively adjacent heat shieldsections joined with the heat shield carrier.

FIG. 16 is a cross-sectional view similar to FIG. 15, but showing inphantom lines the other relatively adjacent heat shield section joinedwith the heat shield carrier.

FIG. 17 is a radially outward view of the heat shield assembly of FIG.16, looking from the line 17-17 of FIG. 16.

FIG. 18 is a fragmentary cross-sectional view of a heat shield takenalong the line 18-18 of FIG. 13.

FIG. 19 is a fragmentary cross-sectional view of a heat shield takenalong the line 19-19 of FIG. 13.

DETAILED DESCRIPTION

The various features and principles of the invention are illustrated byway of three different embodiments, which are described below in detail.

The Embodiment of FIGS. 1-7

Referring now to the drawings in detail and initially to FIGS. 1-6, anexemplary wheel and brake assembly in accordance with one aspect of thepresent invention is indicated generally by reference numeral 10. InFIG. 1, the aircraft wheel and brake assembly 10 is shown mounted on anaircraft bogie axle 12.

The wheel and brake assembly 10 comprises a wheel 14 (only onewheel-half shown for clarity) having a hub 16 and a tube well 18concentric with the hub 16, and a web 20 interconnecting the hub 16 andthe tube well 18. A torque take-out assembly 22 is aligned with the hub16, and the wheel 14 is rotatable relative to the torque take-outassembly 22.

As shown in FIG. 2, a plurality of torque bars 24 are fixed to the wheel14 generally parallel to the axis of rotation 26 of the wheel and spacedfrom the tube well 18. A heat sink 28 is disposed within the wheel 14,and comprises brake or friction disks in the form of rotors 32 andstators 34. The rotors 32 are engaged with the torque bars 24 forrotation with the wheel, and the stators 34 are engaged with the torquetake-out assembly 22 which is fixed against rotation relative to alanding gear strut (not shown). A pressure plate 36 and an end plate 38may be positioned at opposite ends of the heat sink 28 and retainedagainst rotation with respect to the torque take-out assembly 22. Thefriction disks may be formed from any material suitable for frictiondisks, including metals, such as steel with a sintered metallic frictionlining, and ceramics or carbon materials, such as a carbon/carbonmaterial. According to a preferred embodiment, the heat sink 28 is acarbon/carbon composite heat sink having at least one carbon/carbonrotor 32 interleaved with a plurality of carbon/carbon stators 34.

At least one actuator 30 (FIGS. 1 and 2) is provided to compress theheat sink 28. In the example presented, the actuator 30 is ahydraulically actuated piston, but other types of actuators may be usedin the practice of the invention, such as electromechanical actuators.

A heat shield 40, according to one aspect of the invention, is attachedto the wheel 14 between the tube well 18 and the heat sink 28. Asillustrated in FIGS. 1 and 3, the heat shield 40 is concentric with thetube well 18 and has a plurality of heat shield sections 42 disposedbetween respective, relatively adjacent pairs of torque bars 24. Theheat shield sections are spaced from the tube well 18 and secured inplace by respective pairs of heat shield carriers 44 that are fixed tothe wheel 14 generally parallel to the axis of rotation 26 of the wheel14 intermediate the torque bars 24 and the tube well 18. The carriersare preferably aligned with respective torque bars, and have“groove-like” side edges that define edge channels for axially receivingand radially constraining side edge tap portions of the heat shieldsections, as described below with greater particularity.

The torque bars 24 and heat shield carriers 44 are attached at theiraxially inboard end to the wheel 14 by torque bar bolts 48. The torquebar bolts 48 extend through respective holes in a flange provided on thewheel as shown, which flange for purposes of the present description isintended to be considered as part of the tube well. Each torque bar 24preferably has a pin 50 at its axially outboard end (i.e., the endopposite the torque bar bolts 48) that is received within a hole 52 inthe web 20 of the wheel.

After axial insertion between respective pairs of carriers 44, the heatshield sections 42 may be secured in place and to the tube well 18 bysuitable means, such as fasteners, and more particularly heat shieldbolts 54 (FIGS. 1 and 3). Other securement devices may be employed, suchas that described below in relation to FIGS. 8-12 or FIGS. 13-16.

The heat shield sections 42 may be damaged such that replacement isneeded before scheduled maintenance of the wheel and brake assembly. Ifthis occurs, one or more damaged heat shield sections 42 may be replacedby removing the heat shield bolts 54 for those sections, axiallywithdrawing the damaged sections from the wheel and heat assembly,inserting new heat shield sections 42, and replacing the heat shieldbolts 54. This may be accomplished without removing the torque bars 24,thus greatly facilitating field repair of the heat shield 40.

In FIGS. 4A-4F, details of an exemplary torque bar 24 are shown. Eachtorque bar 24 is substantially rectangular-shaped in cross-section (FIG.4F) and has a mounting hole 57 at its axially inboard end that receivesthe torque bar bolt 48.

In accordance with the invention, each torque bar 24 also includes acoupling device in the form of a button 58 for coupling the heat shieldcarrier 44 to the torque bar 24 in the below described manner. As bestshown in FIGS. 4C and 4E, the illustrated button 58 is T-shaped in crosssection and includes a stem portion 59 which extends radially outwardfrom the body of the torque bar 24 to an enlarged, circular-shaped headportion 61. The button 58 is located axially outwardly from the inboardend of the torque bar 24 and preferably is located between the inboardand outboard ends of the torque bar 24. As is also preferred, the button58 is located along the neutral axis of bending of the torque bar 24(i.e., the axial line located midway along the circumferential span ofthe torque bar 24). In the illustrated example, the T-shaped button 58is located about midway between the inboard end and outboard end of thetube well 18.

As seen in FIGS. 1 and 2, the heat shield carriers 44 are generallyradially aligned with the torque bars 24, respectively, and for the mostpart are radially spaced from the respective torque bars 24. Thesuperposing of the heat shield carriers 44 over the torque bars 24minimizes radiation heat transfer from the torque bars to the tube well18. In addition, the space 60 between the torque bars 24 and heat shieldcarriers 44 is preferably filled with air, and serves to insulate theheat shield carriers 44 from the torque bars 24, and reduces the maximumtemperature generated in the heat shield carrier 44 during braking.Reducing the maximum temperature in the heat shield carrier 44 reducesthe amount of heat energy radiated to the tube well 18 during braking,thereby increasing the effectiveness of the heat shield 40. The heatshield carriers 44 may have support portions 56 that rest on the torquebars 24 as shown.

The heat shield 40 and the tube well 18 define an annular space 46therebetween, preferably occupied by air. Preferably, the heat shields40 and/or carriers 44 are restrained from contact with the tube well 18,thereby to prevent fretting or scoring of the tube well 18 and furtherto minimize conductive heat transfer to the tube well 18, both of whichare undesirable. In accordance with the invention, this spacing ismaintained by coupling the heat shield carriers 44 to the torque bars 24to restrict radial movement of the heat shield carriers 44 at a locationaxially spaced from the inboard ends of the carriers 44 that areattached to the tube well 18.

In FIGS. 5A-5E it can be seen that a preferred form of heat shieldcarrier 44 according to an aspect of the invention is preferablygenerally flat, and may be manufactured by forming or stamping a flatpiece of stainless steel (or other suitable material) in a series ofoperations. The heat shield carrier 44 is generally configured as a flatstrip, with an axially extending rib 63 (shown in cross-section in FIG.5E) and a generally oval-shaped rib 65 projecting radially outwardlyfrom the flat strip. The ribs 63 and 65 provide stiffness in and resistbending of the heat shield carrier 44. The heat shield carrier 44 has apair of opposite edges 62 which are generally parallel to the axis ofrotation 26 of the wheel 14, and may be configured as a groove-likeedge. As used herein, the term “groove-like edge” refers to any edgegeometry that receives a tongue or tab structure at the sides of theheat shield sections 42 and restrains inward and outward radial movementof the heat shield sections 42. In the example presented, eachgroove-like edge 62 comprises a pair of axially spaced radially outwardtabs 64 and a radially inward tab 66 disposed between the radiallyoutward tabs 64, with the result being an axially extending channel. Theradially outward tabs 64 may be disposed at the axially inboard andoutboard ends of the heat shield carrier 44 and function to restrainradial movement of an adjacent heat shield section 42 toward the tubewell 18. The radially inward tab 66 is axially spaced from the web 20and configured to restrain radial movement of the heat shield section 42toward the torque bar 24 and/or heat sink 28. Other configurations forthe groove-like edges 62 will become apparent to those skilled in theart, in light of the description provided herein, any of which areconsidered to fall within the purview of the invention. For example,both the tabs 64 and 66 could extend the full length of the edges 62.However, the example presented is inexpensive to manufacture, and isstill effective in restraining radial movement of the heat shieldsections 42.

Referring now to FIGS. 6A-6C, each heat shield section 42 preferablycomprises an upper sheet 72 and a lower sheet 74. The upper sheet 72 maytake the shape of a pan having a lip 76, and is joined to the lowersheet 74 around the circumference of the heat shield section 42 at thelip 76 by suitable means, including spot welding and/or bending a tabfrom the lower sheet 74 around the lip 76. A portion of the lip 76preferably forms a pair of opposite tongue-like edges 78 generallyparallel to the axis of rotation 26 of the wheel 14 (FIG. 1). Jointsthat permit relative movement induced by thermal expansion andcontraction are generally employed, where possible, to provide thermalstress relief and minimize thermal stress warpage of the heat shieldsection 42. In the example presented, tabs from the lower sheet 74 arebent around the lip 76 along edges 78 without rigidly fixing the uppersheet 72 and lower sheet 74 to each other in order to permit relativemovement due to thermal expansion and contraction. The upper sheet 72and lower sheet 74 at one or both of end portions 80 of lip 76 may berigidly fixed by suitable means, including spot and seam welding.Welding only one end portion 80 of lip 76 provides the maximum amount ofmovement for thermal expansion and contraction. In such case, tabs (notshown) from the lower sheet 74 are bent around only one end portion 80of lip 76 opposite the end portion 80 that is welded. In practicehowever, bending tabs from the lower sheet 74 around an arcuate endportion 80 is difficult and increases manufacturing cost, and a heatshield section 42 having the upper sheet 72 and lower sheet 74 weldedtogether at both end portions 80 has been found to be sufficientlyresistant to thermal stress warping. A cup 82 may be inserted through acorresponding hole in the lower sheet 74 and be rigidly fixed to thelower sheet 74 by suitable means, including spot welding.

When completed, the upper sheet 72 and lower sheet 74 define a space 84therebetween. The cup 82 may be configured to help maintain a desiredspacing between the upper sheet and 72 and lower sheet 74 by defining aledge 84 that rests against the upper sheet 72. The space 86 may befilled with only air, but is preferably filled with a suitableinsulating material 88, for example, a ceramic paper. If filled withair, a thin stainless steel foil may be provided as a radiant heatbarrier between the upper sheet 72 and lower sheet 74. The stainlesssteel foil may be dimpled to maintain its position between the upper andlower sheets 72 and 74. The cup 82 provides a heat shield mounting hole90 for receiving a heat shield bolt 54 (FIG. 1) that fixes the heatshield section 42 to the wheel 14. A raised bearing surface 92 may alsobe provided to help ensure that the bulk of the heat shield section 42is spaced from the tube well 18. The upper sheet 72, the lower sheet 74,and the cup 82 are preferably formed from a stainless steel alloy. Theheat shield section 42 may be flat or curved (arcuate), but ispreferably curved in order optimize space inside the wheel and brakeassembly 10, as presented in the drawings. Configuring the heat shieldsections 42 in the manner described herein permits the heat shieldsections 42 to closely follow the geometry of the tube well 18 andoptimize heat shield geometry to maximize heat shielding in theavailable space.

In FIG. 7, the heat shield section 42 is shown engaged with an adjacentelongate heat shield carrier 44. The opposite edges 62 of the heatshield carrier 44 are configured as groove-like edges, and receive thetongue-like edges 78 of the heat shield section 42. Tabs 64 areconfigured to restrain radial movement of the heat shield section 42toward the tube well 18 (FIGS. 1 and 2), and tab 66 is configured torestrain radial movement of the heat shield section 42 toward the torquebar 24 (FIGS. 1 and 2). Thus, the opposite edges 62 of the heat shieldcarrier 44 are configured to cooperate with the heat shield sections 42to restrain radial movement of the heat shield sections 42. The oppositeedges 62 of the heat shield carrier 44 also cooperate with the heatshield sections 42 to restrain rotation of the heat shield sections 42around the heat shield bolts 54. The distance between the tongue-likeedges 78 is dimensioned to allow circumferential thermal expansion andcontraction of the heat shield sections 42 when installed between theheat shield carriers 44. Other geometric configurations will becomeevident to those skilled in the art, and any such variations areconsidered to fall within the purview of this invention.

Reverting to FIGS. 5A-5C, a mounting hole 68 that receives the torquebar bolt 48 is provided in a mounting portion 104 of the heat shieldcarrier 44. As best seen in FIGS. 2 and 3, the mounting portion 104 issandwiched between the torque bar 24 and the insulating spacer 96 whichspaces the carrier 44 and torque bar 24 from the wheel 14 at theattachment location.

The support portion 56 is formed as a tab offset from the body of theheat shield carrier 44 for providing the above-mentioned spacing betweenthe body of the heat shield carrier 44 and the torque bar 24 at theoutboard end of the carrier 44 which is located deep within the well 18of the wheel 14. The support portion 56 has a pair of radially inwardlyextending ears 70 (FIGS. 5B and 5D) for engaging therebetween the torquebar 24, thereby holding the outboard end of the carrier 44 againstcircumferential shifting movement relative to the torque bar 24.

The heat shield carrier is provided with an aperture and moreparticularly a keyhole 110 for receiving and coupling with the button 58of the torque bar 24. The keyhole 110 is thus located axially betweenthe inboard end and outboard end of the tube well 18. The keyhole 110has a combined geometry of an axially extending slot 116 at its axiallyoutboard end and a round hole 118 at the inboard end of the keyhole 110.The slot 116 has a width about equal to the stem 59 of the button 58 andless than the head 61 of the button 58, and the hole 118 has a diameterlarger than the diameter of the head 61 of the button 58 for allowingpassage therethough of the head 61 of the button 58.

Accordingly, each carrier 44 can be assembled in place by first axiallypositioning the carrier 44 with respect to a torque bar 24 such that thekeyhole 110 aligns with the head portion 61 of the button 61 on thetorque bar 24. At this point the head portion 61 of the button 58 can beradially inserted into the hole 118 of the keyhole 110 and then thecarrier 44 and torque bar 24 can be shifted axially relative to oneanother to move the stem portion 59 along the length of the slot 116 ofthe keyhole 110 and thereby engage the carrier 44 with respect to thetorque bar 24. Also, the carrier 44 and torque bar 24 are relativelyaxially shifted to align the hole 68 in the carrier 44 with the hole 57in the torque bar 24, after which the carrier 44 and torque bar 24 canbe secured to the wheel 14 in the above-described manner. When thusassembled, the head 61 of the button 58 will restrain radial outwardmovement of the carrier 44 at a point axially offset from the inboardend of the carrier 44, thereby preventing portions of the carrier 44 andthe heat shield 42 located deep within the well 18 of the wheel 14 fromscoring or otherwise degrading the wheel 14. With such a configuration,the head portion 61 of the button 58 reacts against the centripetalforces on the heat shield carrier 44 during wheel spin-up. In addition,such arrangement eliminates the need for using resilient bumpers tolocate the heat shield carrier 44 deep within the tube well 18 of thewheel 14.

It will be appreciated by those skilled in the art that alternativecoupling devices may be employed to couple the heat shield carrier 44 tothe torque bar 22 for restraining radial movement of the carrier 44within the well 18 of the wheel 14, and such alternatives arecontemplated as falling within the scope of the present invention. Forexample, the torque bar 24 may include a reversely bent tab, or hook,that fits into an aperture, or slot, in the carrier 44 and engages thecarrier 44 as the carrier 44 is axially moved along the torque bar 24.As in the above-described embodiment, the tab restrains radial movementof the heat shield carrier 44 toward the tube well 18.

While the heat shield 40 has been described herein as including aplurality of circumferentially arranged heat shield sections 42 and aplurality of heat shield carriers 44, those skilled in the art willappreciate that the heat shield may comprise a full circle heat shieldor heat shield segments with circumferentially c plural torque bars.Such heat shields and heat shield segments may be equipped with one ormore devices, such as inter-engaging slots and tabs, which will functionto restrain the outboard end and/or intermediate portion of the heatshield or heat shield segments against radially movement.

The Embodiment of FIGS. 8-11

Referring now to FIGS. 8-11, another embodiment of a wheel and brakeassembly according to the invention is indicated generally by referencenumeral 200. Except for the differences described below, the wheel andbrake assembly 200 may be similar to the wheel and brake assembly 10 andlike reference numerals are used to denote like parts and features.

The wheel and brake assembly 200 includes a heat shield assembly 204that is concentric with the tube well 18 and has a plurality of heatshield sections 212 disposed between adjacent torque bars 214 and spacedfrom the tube well 18, and a plurality of heat shield carriers 216 fixedto the wheel 14 generally parallel to the axis of rotation 26 of thewheel 14 intermediate the torque bars 214 and the tube well 18. The heatshield carriers 216 are mounted to the wheel flange of the wheel 14 attheir axially inboard ends by torque bar fasteners 48 and extend axiallyinto the tube well 18. The heat shield carriers 216 include groove-likeedges 62 which receive tongue-like side edges 78 of the heat shieldsections 212 to restrain the heat shield sections 212 from radialmovement. Unlike the afore-described heat shield carriers 44, the heatshield carriers 216 may include resilient bumpers 220 at their axiallyoutboard ends. The resilient bumpers 220 contact the tube well 18 andrestrain radial movement of the heat shield carriers 216 and,accordingly, the heat shield sections 212 engaged by the heat shieldcarriers 216. During wheel spin up, when the heat shield sections 212and heat shield carriers 216 are forced radially outwardly, theresilient bumpers 220 protect the tube well 18 from abrasion. It will beappreciated that, as an alternative to the resilient bumpers 220, thetorque bars 214 and carriers 216 may include respective couplingdevices, such as the above described buttons 58 and keyholes 110, as inthe above-described manner.

As best shown in FIG. 8, the heat shield carrier 216 has an inboard endportion that extends axially beyond the torque bar 212 and then radiallyto define a mounting flange 230. A retainer 234 is mounted to the outerside of the mounting flange 230 by a fastener 236 or other suitablemeans. In the illustrated embodiment, a nut plate 240, which includes aself-locking nut for receiving the fastener 236, is attached to theaxially outboard side of the end flange 230 preferably by a pair ofrivets 242. The rivets 242 extend through respective apertures in theretainer 234 to provide an anti-rotation feature, preventing theretainer 234 from rotating relative to the heat shield carrier 216.Other anti-rotation means may be employed if desired.

As seen in FIGS. 10 and 11, the retainer 234 includes a pair ofcircumferentially spaced ears or tabs 238 extending in oppositedirections for blocking axial withdrawal (i.e., in the axially inboarddirection) of the heat shield section 212 from the respective heatshield carriers 216. Each heat shield section 212 includes a generallyarcuate shaped base portion 250 and abutments 254 projecting radiallyoutwardly from the tongue-like side edge portions 78 of the base portion250. The abutments 254 abut the tabs 64 of the groove-like edges 62 ofthe heat shield carriers 216. In this manner the heat shield sections212 are constrained against axial movement.

Like the afore-described heat shield assembly 40, the heat shieldassembly 204 enables installation and removal of a heat shield section212 without removal of the torque bars 214. However, since the heatshield section 212 is axially confined as above-described, no longermust the heat shield section 212 be secured by a fastener to the tubewell 18 of the wheel 14, thereby eliminating the conduction heat flowpath provided by the fastener.

It will be appreciated by those skilled in the art that the retainers234 could include a single tab 238 for retaining a respective heatshield section 212, in which case only one side edge portion 78 of theheat shield section 212 is axially restrained. A pair of tabs 238,however, provides the advantage of redundancy. It will also beappreciated that the axial retaining feature of the retainer 234 may beaccomplished by alternative geometries or projections, and suchalternatives are contemplated as falling within the purview of thepresent invention. For example, as is illustrated in FIG. 12, a heatshield section 260 may include a slot 262 in one of the side edgeportions 78 thereof, which slot 262 is sized to receive therein a tab264 of a retainer 266. With such arrangement, the tab 264 functions toaxially restrain the heat shield section 260 in both the axially inboardand outboard directions. It is noted that the FIG. 12 arrangement doesnot provide the advantage of redundancy, as the illustrated retainer 266only includes a single tab 264. It will be appreciated that, althoughless practical from an assembly standpoint, redundancy may be achievedby providing the retainer 266 with a pair of tabs 264 (as shown in theFIG. 11 embodiment) and the heat shield sections 260 with slots 262 inboth side edge portions 78 thereof.

The Embodiment of FIGS. 13-16

Referring now to FIGS. 13-16, there is shown a heat shield assembly 304of a wheel and brake assembly according to another aspect of theinvention. FIGS. 13 and 14 show the heat shield assembly 304 in anunassembled condition, and FIGS. 15 and 16 show the heat shield assembly304 in a partially assembled condition. Except for the differencesdescribed below, the heat shield assembly 304 forms part of a wheel andbrake assembly that is similar to the wheel and brake assemblies 10 and200. Throughout the figures, like reference numerals designate like orcorresponding parts.

Like the afore-described heat shield assembly 204, the heat shieldassembly 304 is concentric with the tube well 18 and has a plurality ofheat shield sections 312 disposed between relatively adjacent torquebars 214 and a plurality of heat shield carriers 316 fixed to the wheel14 and spaced from the tube well 18. The heat shield carriers 316 extendgenerally parallel to the axis of rotation 26 of the wheel 14 betweenthe torque bars 214 (shown in dashed lines) and the tube well 18. Theheat shield carriers 316 are mounted at holes 317 to the wheel 14 attheir axially inboard ends by torque bar fasteners 48 and extend axiallyinto the tube well 18. The heat shield sections 312 are mounted at holes319 to the tube well 18 at their axially inboard ends by the heat shieldfasteners 54 (not shown) and extend circumferentially between relativelyadjacent heat shield carriers 316.

In the illustrated exemplary embodiment, each heat shield carrier 316includes a reversely bent side edge portion 320 that is J-shaped incross-section and defines an inwardly opening, axially extending captureslot 324. The other or opposite side edge portion 322 of the carrier 316is relatively flat. The width of the heat shield carrier 316 is suchthat when the inboard end of the heat shield carrier 316 is mounted to atorque bar 214 the bent side edge portion 320 preferably extendscircumferentially beyond the axial edge of the torque bar 214.

The bent side edge portion 320 of the heat shield carrier 316 hasextending therethrough one or more apertures 330. In the illustratedembodiment, two apertures 330 are axially spaced apart along the lengthof the side edge portion 320. The apertures 330 extend circumferentiallythrough the radially extending wall portion 326 of the side edge portion320 and also radially through the radially inward wall portion 328 ofthe bent side edge portion 320.

Each heat shield section 312 includes opposite insulating side edgeportions 336 and 338, and a relatively thick insulating portion 340between the insulating side edge portions 336 and 338. The heat shieldsection 312 may be manufactured of the same materials and constructed ina manner similar to that of the above-described heat shield sections 42or 204. For example, as shown in FIGS. 18 and 19, which arecross-sectional views of the insulating side edge portions 336 and 338,respectively, as well as a portion of the central insulating portion340, the space between upper 337 and lower sheets 339 of the heat shieldsection 312 may be filled with ceramic paper 341. Alternatively, asabove-mentioned, the space may be filled with air, in which case the airwould function as the insulator. It will be appreciated that the upper337 and lower sheets 339 themselves also provide insulation, evenwithout ceramic paper or air therebetween.

The side edge portion 336 has one or more circumferentially extendingtabs 342. In the illustrated embodiment, three axially spaced-apart tabs342 a-c are provided and define therebetween respective relief portions344 a and 344 b. Alternatively, the side edge portion could be viewed asa single flange or tab which is provided with one or more reliefs forthe reasons hereinafter described.

The other side edge portion 338 of each heat shield section 312 has anouter side edge 350 from which project one or more tabs 352. In theillustrated embodiment, two axially spaced-apart tabs 352 are provided.Each tab 352 has an axially extending hook portion 358 extendinggenerally parallel to the adjacent outer side edge 350 andcircumferentially spaced from the outer side edge 350 to form an axiallyopening slot 360. In the illustrated embodiment the slots 360 opentowards the inboard end of the carrier 316 as is preferred.

As seen in FIG. 13, tabs 352 and apertures 330 are correspondingly sizedand axially spaced apart such that the tabs 352 can be aligned with theapertures 330 for radial passage into the apertures 330. After the tabs352 have been inserted into the apertures 330, the heat shield section312 is shifted axially inwardly to engage the hook portion 358 under theradially inner wall 328 of the side edge portion 320 of the carrier 316.In this manner, the tabs 352 can be radially restrained between theradially inner wall 328 of the side edge portion 320 and the radiallyouter wall of the apertures 330 or radially outer wall portion 362 ofthe side edge portion 320, whereby the carrier 316 will restrain radialmovement the thus interlock side 338 of the heat shield section 312.

As also seen in FIG. 13, the apertures 330 and the reliefs 344 a-b arecorrespondingly sized and axially spaced apart such that when the tabs342 a-c are inserted into the slot 324 formed by the side edge portion320 of the carrier 316, the reliefs 344 a-b will generally align withthe apertures 330. Also, the reliefs 344 a-b are of sufficient size toavoid interference with the tabs 352 when the latter are inserted intothe apertures 330 and engaged with the carrier 316.

In FIG. 15, the side edge portion 336 of the heat shield section 312 isshown inserted into the slot 324 of the side edge portion 320 of thecarrier 316. To accomplish this, the heat shield section 312 is firstinserted axially into the tube well 18 of the wheel 14 towards theoutboard end of the wheel 14. The side edge portion 336 is thencircumferentially inserted into the capture slot 324 of the bent sideedge portion 320 of the carrier 316. Simultaneously, the tabs 352 on theopposite side edge portion 338 of the heat shield section 312 areaxially aligned with the apertures 330 in the side edge portion 320 ofthe there-adjacent heat shield carrier 316, after which the heat shieldsection 312 can be pivoted radially outwardly to move the tabs 352 intothe apertures 330 and fully seat the side edge portion 336 of the heatshield section 312 in the slot 324 of the other carrier 316. The sideedge portion 320 of the heat shield carrier 316 in this manner securelyengages the tabs 342 a-c of the heat shield section 312 to restrainradially outward and inward movement of the side edge portion 336 of theheat shield section 312.

Referring now to FIG. 16, solid lines are used to show a heat shieldsection 312 already installed in relation to a heat shield carrier 316as in the manner shown in FIG. 15, while phantom lines are used to showthe manner in which a next adjacent heat shield section 312′(differentiated by the use of primed reference numbers) is installed inrelation to the same heat shield carrier 316. As above described, thetabs 352′ on the side edge portion 338′ of the heat shield section 312′are axially aligned with the apertures 330 in the side edge portion 320of the there-adjacent heat shield carrier 316, after which the heatshield section 312′ can be pivoted radially outwardly to move the tabs352′ into the apertures 330. At this point the tabs 352′ will lie in theplane of the capture slot 324 of the side edge portion 320. The heatshield section 312′ is then moved axially towards the inboard end of thewheel 14, whereby the hook projections 358′ of the tabs 352′ will beradially captured by the side edge portion 320 of the carrier 316. Oncefully engaged, the tabs 352′ securely engage the carrier 316 therebyrestraining the side edge portion 338′ of the heat shield section 312′against radially outward and inward movement. Also, the bolt 54 securesthe heat shield section 312′ against axial movement.

The just-described mounting arrangement of a heat shield section 312between relatively adjacent carriers 316 enables both reduced thicknessinsulated side edge portions 336 and 338 of the respective adjacent heatshield sections 312 at the common carrier 316 to be radially restrainedover a relatively small circumferential span and in the same captureplane, as is preferred. However, other arrangements are alsocontemplated although less desirable. For example, the side edge portion336 may be a straight edge (i.e., without tabs and intermediate reliefportions) which, when inserted circumferentially into the bent side edgeportion 320, extends only partially into the capture slot 324, leavingenough circumferential space for the hook tabs 352 to slide into thecapture slots 324 and engage with the side edge portion 320 of thecarrier 316.

As illustrated in FIGS. 14 and 16, the above-described mountingarrangement enables the insulating side edge portions 336 and 338 andthe relatively thick insulating portion 340 of each heat shield section312 to span not only the circumferential space between relativelyadjacent torque bars 214 but also to extend between the torque bar 214and the tube well 18. This enables heat shielding substantiallyequivalent to that provided by a single tubular heat shield thatcircumscribes all of the torque bars 214, while providing the benefitsafforded by the use of plural heat shield sections.

Although the invention has been shown and described with respect tocertain embodiments, equivalent alterations and modifications will occurto others skilled in the art upon reading and understanding thisspecification and the annexed drawings. In particular regard to thevarious functions performed by the above described integers (components,assemblies, devices, compositions, etc.), the terms (including areference to a “means”) used to describe such integers are intended tocorrespond, unless otherwise indicated, to any integer which performsthe specified function of the described integer (i.e., that isfunctionally equivalent), even though not structurally equivalent to thedisclosed structure which performs the function in the hereinillustrated exemplary embodiments of the invention. In addition, while aparticular feature of the invention may have been described above withrespect to only one of several illustrated embodiments, such feature maybe combined with one or more other features of the other embodiments, asmay be desired and advantageous for any given or particular application.

1. A heat shield assembly for a wheel and brake assembly, comprising: acircumferential arrangement of heat shield sections; a plurality ofaxially extending heat shield carriers between which respective heatshield sections are axially inserted; and at least one retainerremovably secured with respect to a respective carrier for abutting anaxial end face of at least one heat shield section to block axialwithdrawal of the heat shield section from respective carriers.
 2. Aheat shield assembly as set forth in claim 1, wherein the retainer issecured to an axial end of the carrier by an axially extending fastener.3. A heat shield assembly as set forth in claim 2, wherein the retainerand axial end of the carrier include coacting anti-rotation elements. 4.A heat shield assembly as set forth in claim 1, wherein at least one ofthe carriers has an axial stop against which a portion of the respectiveheat shield section abuts to limit the extent of axial insertion of theheat shield section with respect to the carrier.
 5. A heat shieldassembly as set forth in claim 4, wherein each carrier has on oppositesides thereof upper and lower tabs defining axially extending channelsfor receiving edge portions of circumferentially adjacent heat shieldsections.
 6. A heat shield assembly as set forth in claim 5, wherein theaxial stop is formed by an axial end of one of the tabs.
 7. A heatshield assembly as set forth in claim 6, wherein each heat shieldsection includes at a side edge thereof a projecting abutment forengaging the axial stop.
 8. A wheel and brake assembly comprising awheel having an axis of rotation and including a tube well havinginboard end and outboard ends; at least one torque bar attached to thetube well for transferring torque from the wheel to brake componentslocated radially inwardly of the tube well, the torque bar extendinggenerally parallel to the axis of rotation of the wheel and spacedradially inwardly from the tube well; and the heat shield assembly ofclaim 1 concentric with and disposed radially inwardly of the tube well.